The effects of two anticholinergic drugs on heat production (derived from oxygen consumption), sweating and core and skin temperature were compared with saline placebo in five healthy volunteers, before and after exercise. There were no significant differences between the groups in resting and peak heat production after exercise. Sweat evaporation rate increased after exercise in all cases, but there was individual variation in response to the drugs. Sweat evaporation was greater after saline placebo compared with atropine, but not after glycopyrrolate compared with saline placebo or atropine. In the saline placebo group, increased sweat evaporation following exercise was reflected by an initial fall, in skin temperature. Following anticholinergic drugs, skin temperature increased after exercise without an initial decrease. Core temperature increased following exercise, but there were no significant differences between the anticholinergic drugs and saline placebo. Although clinical doses of anticholinergic drugs, when compared with saline placebo, inhibited sweating after exercise, core temperature was not significantly increased. Therefore it is suggested that non-evaporative heat loss compensated for the reduction in sweating due to anticholinergic drugs.